Excess-wattmeter.



A. W. BURKE. EXCESS WATTMETER. APPLICATION FILED MAR. 2, 1915.

Patented Apr. 16, 1918.

1 saw/cs MAI/V6 i SERVICE MAI/VS M MQ Q un KIEITED Fro.

ALFRED w. BunKnor WILMINGTON, DELAWARE.

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To all whom it may concern:

Be it known that I, ALFRED W. BURKE, a subject of the King of Great Britain, residing at Wilmington, in the county of New Castle and State of Delaware, have invented certain new and useful Improvements in Excess-Wattmeters, of which the following is a specification.

This invention relates to recording wattmeters, such as are used on alternating current circuits, for recording the electrical energy consumed in excess of a certain predetermined quantity, and has for its object to provide a compensator to automatically correct the error in watt-meters of this kind, due to an increase or decrease in line voltage. The invention is an improvement on that described in my Patent No. 1,175,508, patented March 14, 1916.

In my copending application, a neutralizing and balancing coil, of a predetermined electrical value, operates to neutrallze and balance the series coil of the watt-meter, to the value of the electrical energy contracted for, any excess electrical energy used being recorded by the meter. With a line voltage of substantially constant value, the wattmeter records correctly, but with variations in the line voltage, errors are introduced as hereinafter described.

In the present case, the improvement c0nsists in adding a compensator to correct the error due to the fluctuation in line voltage, whereby the accurac of the meter is considerably increased, t e function of the compensator being to supply an electromotlve force, and also a current, of as nearly as possible constant value, to neutralize or balance potential at the terminals of, or the magnetic flux of, the series coil of the wattmeter, regardless of the variation 1nl1ne voltage. The compensator is a specially designed transformer, operating at above the magnetic saturationpoint of the iron core, whereby a substantially uniform potential is induced in its secondary, notwithstanding considerable variations in the line voltage.

In the accompanying drawings- Figure 1 is a diagram showlng one method of electrical connections for an excess watt-meter, including the compensator;

Fig. 2 is a dlagram of the meter connections, showing the compensator connected to a neutralizing coil;

Fig. 3 is a diagram of the meter connections without the compensator; and

Specification of Letters Patent. Patented Apr, 16, 1918,

Application filed. March 2, 1915.

Serial No. 11,484.

ing the usual series coil 7 and shunt coil 8,

is connected in the usual manner in the circu1t. A. transformer 9, which may be of the step-down type, supplies current to a compensator 10, which consists of a specially designed transformer operated at above the magnetic saturation point of the iron core, whereby a substantially uniform potential is induced in its secondary, notwithstanding considerable variations in the line voltage.

Adjustable resistances 11, 12, either of.

which may be omitted, are connected as shown, in the primary and secondary of the compensator, to adjust the meter to local conditions; and taps 13, lead fromthe sec-,

ondary of the compensator providing a variety of potentials, thereby adapting the meter for use on a great variety 'ofcircuits;

the secondary of the compensator being connected tothe terminals of the series coil 7 of the watt-meter in such a manner that the 7 magneticeffects of the current in its series coil are opposed and neutralized by the compensator current. When properly ad:

justed, and the contracted-for current is being consumed in the house circuit, the mag. netic elfects of the series 0011 7 are balanced,

as above described, and the watt-meter .is

not actuated. When thecurrent consumed in the house mains exceeds the contractedfor value, the excess overthis value is not neutralized or balanced, and accordingly actuates the meter to the extent of the excess and is recorded. By suitably winding and adjusting, a second compensator could be substituted for the transformer 9, there by giving still greateraccuracy.

In Fig. 2, current passes from the service mains through the house mains 3 to the translating devices 5. A watt-meter 6, containing the usual series coil 7 and shunt coil 8, is connected in the regular manner in the circuit. A compensator 10 is connected by its primary through the adjustable resistance 12 across the house mains 3;

the secondary of the. compensator having 1 taps 13, is connected to the coil 25 which is constructed and located so as to magnetically neutralize and balance the magnetic efiect of the series coil 7 upon the rotating. element of the wattmeter when the contractedfor current is passing through the series coil. The compensator is initially adjusted by the resistance 12 and the taps l3,.aszdescriloed under Fig. 1, an excess current in the houseniaiiis being recorded as described under Fig. 1.

Fig. 3 illustrates the general method of operation described and claimed in my pat- :ent above referred to. Current from the service mains passes through 01 switch 15 to the house mains'l6,-supp lying the translating devices 17,}a watt-meter 18, containing the series coil-1'9 and shunt coil 20 being con nected in thecircuit in the usual-manner. .Asmall transformer 21 is connected across "the house mains, as shown, itssecondary being--connectedthrough an adjustable resistance Q2 and then to the terminals ofthe series coil 19 of the meter as shown, but not including a compensator- 10'described in con- :nection with Fig. 1. This method of operating --gives -entirely: reliable results upon cir- :ouits of substant-iallyuniform voltage; but with wide fiuctuations in line voltage, it --gives less reliable service. By suitably *windingand adjusting the compensator, it

could alsobe -useddirect in, place of trans- 'tormer 21.

In the above illustrations, resistances 11,

'"12,12.',-aiid-"22, may be of-either the induc- 'tive or non-inductive type.

' lir Eigat, are shown curves A and B, illustrating; the watts recorded by the watt-meter at "varying voltages, curve; A showing the --record when thewatt-meter is connected as shown in Fig. 1, with the compensator while curve'= B shows" the record or the watt-meter when connected. as in' Fig. 3, without the compensator; the curves being made from actual tests. Assuming a voltage of 100,

wand the watts consumed 140,- an increase in iliILH'VOltagB of 5 volts-increases the watt- -meter recordfrom 140 to 145, an increase of 5, on curve A, with the compensator while without the compensator, curve 113, the recorded wattageis l-55, an increase of'15, or 'bhIQBtI-HIGS'tlIG error. If the line voltage should increase to I 115, the recorded watts -with the compensator would be 158, an-increase of18, as shown on curve A; while without the compensator, curveB, it would be 202, an increase of 62,; or about?3.-5 times the error. With reduced voltages,-v the coinpensator also gives morereliable records;

'w'ith 95 vo'lts on the'iline, curve :A- showsa record or 132.5- WttlltSyEtdBOlGfiSG of 7 .5; while "curve B-shows125 watts,a decrease oif 15,-=or

twice the error. 7

The operation of the watt-meter is otherwise the/same asdescr-ibed in nay-prior patout, above referred to; the compensator. may be applied to any of the difl'erent arrangements of circuits described in that patent.

.Tlie -operation of the watt-meter as connected in Figs. 1, 2, and 3, above described, voit. thisapplication will serve to illustrate its general application.

As shown :inll ig. 5, the rotation of the rotatable armature 4-2 of the watt-meter in the reverse directionisprevented by the use of a suitable brake such as an intermittent- "grip device, a pawl-andrratchet 4O1being voltage, the secondary circuit of said-com- --pensator electrically connectedso as. to nontra'lize andbalancethe magnetic ef'iect of said coil.

5 2. i Inanapparatus' for measuring electric currents, a =watt-ineterfihaving a series coil, a compensator connected to balaiiceisaidcoil,

saidcompensatorconstructed to supply a a current at substantially amiform: voltage.

3. 1 In apparatus formeasuring electric currents, a wattmeteri having a series. .0011,

compensator,the-secondary of said comlpensator' connected to therterini-nals: of said -'S8116S' coil.

=4. In anapparatus for: measuring electric '5. In a system "for iiieasuring electrical energy the combinat on witha meter'haviiig 'a-cui'rent coil of means-connected toithe. line 4301' producing an'dwmaintaining across the "terminals of said current c011 at counterE.

F. having a substantially eonstantpre deter-mined value-iiotwithstand;uig variations in the line voltage.

- 6. A-n electricmeter= comprising. in com- 7 bination a rotatable armature,electromagnetic means for rotating saidharinaturef and tending to produce a magnetic field which is 1 a function it of f the rate :of-consumption of electric energy, and imeans, comprising a saturated core transformer whose 1311111313 coil sarranged I to r be energized E'fDOllL the supp-1y circuit to which the aneterisadapted' to be connected, for negativing the effect "of saicl'electromagnetic means +while. the i rate of consumption of energy. .is' less 'than a predetermined value and for oflering a substan- *tially constant opposition to such electro- I magnetic means while. the-rate of. consumption of energy equals or exceeds said predetermined value, and means for registering the revolutions of said armature.

7. In an electrical measuring instrument the combination of electromagnetic means for producing a magnetic field which is a function of the line current and means comprising a saturated core transformer whose primary coil is arranged to be energized from the supply circuit to which the measuring instrument is adapted to be connected for neutralizing the magnetic efiect of such electromagnetic means while the rate of ourrent-flow is less than a predetermined value and for ofiering a substantially constant 0pposi'tion to such electromagnetic means while the rate of current-flow equals or exceeds said predetermined value. p

8. In an electrical measuring instrument the combination of a rotatable armature, electromagnetic means for rotating said armature and tending to produce a magnetic field which is a function of the line-current and means, comprising a saturated core transformer whose primary coil is arranged to be energized from the supply circuit to which the measuring instrument is adapted to be connected for neutralizing the magnetic efl'ect of such electromagnetic means while the rate of current-flow is less than a predetermined value and for offering a substantially constant opposition to such electromagnetic means while the rate of current-flow equals or exceeds said predetermined Value.

In testimony whereof I atfix my signature in presence of two witnesses.

ALFRED W. BURKE.

Witnesses S. A RAMsoN, ALFRED WHARTENBY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

